// not exist.
	//
	// The context is associated and tied to the generated DEK.
	// The same context must be provided when the generated key
	// should be decrypted. Therefore, it is the callers
	// responsibility to remember the corresponding context for
	// a particular DEK. The context may be nil.
	GenerateKey(ctx context.Context, keyID string, context Context) (DEK, error)